Chapter 7

Determine whether each of the following is true or false. If false, explain why. a) An array can store many different types of values. b) An array index should normally be of type float. c) An individual array element that is passed to a method and modified in that method will contain the modified value when the called method completes execution. d) Command-line arguments are separated by commas.

Perform the following tasks for an array called fractions: a) Declare a constant ARRAY_SIZE that is initialized to 10 . b) Declare an array with ARRAY_SIZE elements of type double, and initialize the elements to 0 c) Refer to array element 4 d) Assign the value 1.667 to array element 9 e) Assign the value 3.333 to array element 6 f) Sum all the elements of the array, using a for statement. Declare the integer variable \(x\) as a control variable for the loop.

Perform the following tasks for an array called table: a) Declare and create the array as an integer array that has three rows and three columns. Assume that the constant ARRAY_SIZE has been declared to be 3 . b) How many elements does the array contain? c) Use a for statement to initialize each element of the array to the sum of its indices. Assume that the integer variables \(x\) and \(y\) are declared as control variables.

Write Java statements to accomplish each of the following tasks: a) Display the value of element 6 of array \(f\) b) Initialize each of the five elements of one-dimensional integer array \(g\) to 8 c) Total the 100 elements of floating-point array \(c\). d) Copy 11 -element array a into the first portion of array \(b\), which contains 34 elements. e) Determine and display the smallest and largest values contained in 99 -element floatingpoint array w.

Consider a two-by-three integer array t. a) Write a statement that declares and creates t. b) How many rows does t have? c) How many columns does t have? d) How many elements does t have? e) Write access expressions for all the elements in row 1 of \(t\) f) Write access expressions for all the elements in column 2 of t. g) Write a single statement that sets the element of t in row 0 and column 1 to zero. h) Write a series of statements that initializes each element of t to zero. Do not use a repetition statement. i) Write a nested for statement that initializes each element of t to zero. j) Write a nested for statement that inputs the values for the elements of t from the user. k) Write a series of statements that determines and displays the smallest value in t. I) Write a printf statement that displays the elements of the first row of t. Do not use repetition. m) Write a statement that totals the elements of the third column of t. Do not use repetition. n) Write a series of statements that displays the contents of \(t\) in tabular format. List the column indices as headings across the top, and list the row indices at the left of each row.

(Duplicate Elimination) Use a one-dimensional array to solve the following problem: Write an application that inputs five numbers, each between 10 and 100 , inclusive. As cach number is read, display it only if it is not a duplicate of a number already read. Provide for the "worst case," in which all five numbers are different. Use the smallest possible array to solve this problem. Display the complete set of unique values input after the user enters each new value.

Write an application that calculates the product of a series of integers that are passed to method product using a variable-length argument list. Test your method with several calls, each with a different number of arguments.

Write an application that uses an enhanced for statement to sum the double values passed by the command-line arguments. [Hint: Use the static method parseDouble of class Double to convert a String to a double value.

(Dice Rolling) Write an application to simulate the rolling of two dice. The application should use an object of class Random once to roll the first die and again to roll the second die. The sum of the two values should then be calculated. Each dic can show an integer value from 1 to \(6,\) so the sum of the values will vary from 2 to \(12,\) with 7 being the most frequent \(\operatorname{sum},\) and 2 and 12 the least frequent. Figure 7.30 shows the 36 possible combinations of the two dice. Your application should roll the dice 36,000 times. Use a one-dimensional array to tally the number of times each possible sum appears. Display the results in tabular format. Determine whether the totals are reasonable (c.g., there are six ways to roll a \(7,\) so approximately one-sixth of the rolls should be 7 ).

(Airline Reservations System) A small airline has just purchased a computer for its new automated reservations system. You have becn asked to develop the new system. You are to write an application to assign seats on cach flight of the airline's only plane (capacity: 10 seats). Your application should display the following alternatives: Please type 1 for First Class and Please type 2 for Economy. If the user types \(1,\) your application should assign a scat in the firstclass section (seats \(1-5\) ). If the user types 2 , your application should assign a seat in the economy section (scats \(6-10\) ). Your application should then display a boarding pass indicating the person's seat number and whether it is in the first-class or economy section of the plane. Use a one-dimensional array of primitive type boolean to represent the seating chart of the plane. Initialize all the elements of the array to false to indicate that all the seats are empty. As each seat is assigned, set the corresponding elements of the array to true to indicate that the seat is no longer available. Your application should never assign a seat that has already been assigned. When the economy section is full, your application should ask the person if it is acceptable to be placed in the first-class section (and vice versa). If yes, make the appropriate seat assignment. If no, display the message "Next flight leaves in 3 hours."